Codex may run many per-thread proxy instances, so hardcoded proxy ports
are brittle and conflict-prone. The previous "ephemeral" approach still
had a race: `build()` read `local_addr()` from temporary listeners and
dropped them before `run()` rebound the ports. That left a
[TOCTOU](https://en.wikipedia.org/wiki/Time-of-check_to_time-of-use)
window where the OS (or another process) could reuse the same port,
causing intermittent `EADDRINUSE` and partial proxy startup.
Change the managed proxy path to reserve real listener sockets up front
and keep them alive until startup:
- add `ReservedListeners` on `NetworkProxy` to hold HTTP/SOCKS/admin std
listeners allocated during `build()`
- in managed mode, bind `127.0.0.1:0` for each listener and carry those
bound sockets into `run()` instead of rebinding by address later
- add `run_*_with_std_listener` entry points for HTTP, SOCKS5, and admin
servers so `run()` can start services from already-reserved sockets
- keep static/configured ports only when `managed_by_codex(false)`,
including explicit `socks_addr` override support
- remove fallback synthetic port allocation and add tests for managed
ephemeral loopback binding and unmanaged configured-port behavior
This makes managed startup deterministic, avoids port collisions, and
preserves the intended distinction between Codex-managed ephemeral ports
and externally managed fixed ports.
This PR adds the following field to `Config`:
```rust
pub network: Option<NetworkProxy>,
```
Though for the moment, it will always be initialized as `None` (this
will be addressed in a subsequent PR).
This PR does the work to thread `network` through to `execute_exec_env()`, `process_exec_tool_call()`, and `UnifiedExecRuntime.run()` to ensure it is available whenever we span a process.
Summary:
- Rename config table from network_proxy to network.
- Flatten allowed_domains, denied_domains, allow_unix_sockets, and
allow_local_binding onto NetworkProxySettings.
- Update runtime, state constraints, tests, and README to the new config
shape.
### Summary
- Adds an optional SOCKS5 listener via `rama-socks5`
- SOCKS5 is disabled by default and gated by config
- Reuses existing policy enforcement and blocked-request recording
- Blocks SOCKS5 in limited mode to prevent method-policy bypass
- Applies bind clamping to the SOCKS5 listener
### Config
New/used fields under `network_proxy`:
- `enable_socks5`
- `socks_url`
- `enable_socks5_udp`
### Scope
- Changes limited to `codex-rs/network-proxy` (+ `codex-rs/Cargo.lock`)
### Testing
```bash
cd codex-rs
just fmt
cargo test -p codex-network-proxy --offline
This add a new crate, `codex-network-proxy`, a local network proxy
service used by Codex to enforce fine-grained network policy (domain
allow/deny) and to surface blocked network events for interactive
approvals.
- New crate: `codex-rs/network-proxy/` (`codex-network-proxy` binary +
library)
- Core capabilities:
- HTTP proxy support (including CONNECT tunneling)
- SOCKS5 proxy support (in the later PR)
- policy evaluation (allowed/denied domain lists; denylist wins;
wildcard support)
- small admin API for polling/reload/mode changes
- optional MITM support for HTTPS CONNECT to enforce “limited mode”
method restrictions (later PR)
Will follow up integration with codex in subsequent PRs.
## Testing
- `cd codex-rs && cargo build -p codex-network-proxy`
- `cd codex-rs && cargo run -p codex-network-proxy -- proxy`
Michael Bolin ·
viyatb-oai ·